In recent years, there has been an increasing need to use technologies to monitor health and fitness. Providing users with real-time and accurate information about their daily activities in a non-intrusive manner has become a promising approach. Using these technologies for tracking activities, users can adjust their daily activities, to meet their personal fitness goals, for example. Also, in casual and competitive sports, users want to see their performance (e.g., running speed, jump height, stride length, etc.) in real-time and make adjustments in their training routine to meet the performance goals. The implementation of activity tracking relies on the use of sensors. The sensors may include accelerometers, gyroscopes, magnetometers, barometers, temperature sensor, etc. To allow continuous tracking of user activities, the sensors are normally worn on the user's body. These sensors can be placed on one or multiple locations on the user's body depending on the application. To be more useful, the activities are tracked continuously for a prolonged period of time.